Interpretive Summary: Grassland insect diversity is often linked to plant species composition and habitat structure, with insect herbivore diversity thought to generally increase with increased plant species richness due to increased resource diversity. It remains a continuing challenge in grasshopper ecology to understand what determines species diversity in a given area. In most grassland ecosystems the nature of relationships between plant species richness and grasshopper abundance remains unclear. In this system with relatively low plant diversity, grasshopper species richness and abundance was not associated with plant species richness. Although a number of significant associations between plant species richness and diversity were found in this study, results differed between years. Most grasshopper species found are generalists that feed on multiple plant species. As a result, plant species richness appears to be too coarse grained to lead to accurate predictions of grasshopper species richness.

Technical Abstract:
A continuing challenge in Orthoptera ecology is to understand what determines grasshopper species diversity at a given site. In this study, the objective was to determine if variation in grasshopper abundance and diversity between 23 sites in western North Dakota (USA) could be explained by variation in plant species richness and diversity. In this system with relatively low plant diversity, grasshopper species richness and abundance was not associated with plant species richness. Although a number of significant associations between plant species richness and diversity were found through the regression analyses, results differed greatly between years. Plant species richness appears to be too coarse grained to lead to accurate predictions of grasshopper species richness in this system.